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A series of new symmetrical highly substituted BODIPYs 6 a-l was synthesized through a prefunctionalization approach in 35 %-89 % yields from the pyrrole core. This strategy allowed modulation of the substituents at the different positions based on the choice of Fischer's alkynyl carbenes, oxazolones and aldehydes used as precursors. The substituent variation at positions 2, 6, 3 and 5 had the greatest effect on the modulation of their photophysical properties such as absorption (λ

Two series of 2,5-di(butoxy)phenyleneethynylenes, one halogenated (nPEC4-X; n=2, 3, or 4) and the other boron-dipyrromethene (BODIPY) terminated (nPEC4-By; n=3, 4, or 5; By=BODIPY), were synthesized monodirectionally by the step-by-step approach and the molecular structure was corroborated by NMR spectroscopy (1 H, 13 C-DEPTQ-135, COSY, HSQC, HMBC, 11 B, 19 F) and MALDI-TOF mass spectrometry. The multiplicity and J-coupling constants of 1 H, 11 B, and 19 F/11 B NMR signals revealed, in the nPEC4-By series, that the phenyl in the meso position of BODIPY becomes electronically part of the conjugation of the phenyleneethynylene chain, whereas BODIPY is electronically isolated. The photophysical, electrochemical, and theoretical studies confirm this finding because the properties of nPEC4-By are comparable to those of the nPEC4-X oligomers and BODIPY, indicating negligible electron communication between BODIPY and the nPEC4 moieties. Nevertheless, energy transfer (ET) from nPEC4 to BODIPY was rationalized by spectroscopy and theoretical calculations. Its yield decreases with the nPEC4 conjugation length, according to the increase in distance between the two chromophores, resulting in dual emission for the longest oligomer in which ET is quenched.

The synthesis of a 2,5-bis(dodecanoxy)phenyleneethynylene-butadiyne series with 2, 4, 6 and 8 phenyl rings is reported. Sonogashira coupling reaction, rather than the Glaser/Eglinton/Hay reactions classically used for butadiyne formation was applied. The molecular structures of all compounds were confirmed by 1H, DEPT-135, APT 13C, MALDI-TOF, FTIR and FT-Raman analyses. The linear and nonlinear optical properties were studied in solution by UV/Vis, static and time-resolved fluorescence, and by two-photon absorption (2PA) spectroscopy. With the exception of the dimer, for which intersystem crossing is very favoured due to the low energy gap between the singlet and triplet states as theoretically predicted, the other oligomers present high fluorescence quantum yields (0.77–0.82) and large cross-sections (up to 5000 GM for the octamer) that could be applied in multiphoton microscopy or nonlinear optics.

Polymer nanocomposites of an epoxy resin with natural montmorillonite (MMT), organically modified montmorillonite(OMMT), and halloysite nanotubes(HNTs) were prepared by the solvent casting method. Photoluminescence (PL) measurements showed that the epoxy nanocomposites with OMMT and HNTs give rise to a red-shift of the emission band associated to bisphenol groups and to well resolved emission spectra, attributable to coplanar packing of the polymer chains in the excited states. A significant PL quenching in all the nanocomposites was observed, which depended on type and clay concentration. Atomic force microscopy (AFM) images showed a greater penetration of the epoxy resin only into the OMMT and HNT agglomerates. A relationship between the PL behavior and both the extent of confinement of polymer chains in clays agglomerates and the changes in the formation of trapping sites produced from hydroxyl groups could be revealed by AFM images and Fourier transform infrared spectroscopy (FTIR) studies. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

We report on the preparation and spectroscopic characterization of a novel nanocomposite consisting of silver nanoparticles and a fluorescent polymer obtained by in situ ps laser ablation of a silver target. While the polymer is able to detect the fungus Paecilomyces variotii by fluorescence quenching, the composite with silver nanoparticles permits an interaction with both cell walls of spores and mycelia without any appreciable reduction of the overall fluorescence quantum yield.